KR20140043038A - Vehicle path estimation method and apparatus, and vehicle steering control method and apparatus - Google Patents

Abstract

Disclosed is a method to calculate a vehicle path to avoid obstacles or change a path. The method includes a step of determining a target position to avoid obstacles or change a path based on the current position of a vehicle and a step of calculating a changed temporal or spatial vehicle path by producing intermediate parameters using a steering angle control pattern model extracted from a driving behavior pattern model based on the determined target position.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a vehicle path estimation method and apparatus,

The present invention relates to an unmanned traveling of an automobile, and more particularly, to a route setting algorithm that utilizes a general driving steering pattern of a human being. The present invention satisfies the kinematic restriction condition of an automobile, And more particularly, to a method and an apparatus for calculating a vehicle path that can be applied even in the absence of a vehicle.

As an existing technique for controlling the steering and the speed of a car so as to move along a planned route when the current position and direction of the vehicle are different from the attitude on the given route in the unmanned traveling of the vehicle, And vector pursuit. However, according to the conventional technology, a follow-up point is calculated based on a momentary position of a vehicle, and the steering angle is controlled. When the current position of the vehicle is different from the actual position or an obstacle appears suddenly, The rider can feel uncomfortable due to the generation of a large centrifugal force by a sudden turning control steering.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems and to solve the above-mentioned problems, and an object of the present invention is to provide a route guidance system, There is provided a method and apparatus for calculating a vehicle path and a method and an apparatus for controlling the steering of a vehicle that are capable of acquiring familiarity and comfort of the rider by following human tendency while ensuring continuity of the steering angle over time .

According to another aspect of the present invention, there is provided a vehicle path calculating method comprising: determining a target position for avoiding an obstacle or changing a path of a vehicle based on a current position of the vehicle; And calculating the changed spatial or temporal vehicle path by calculating the parameter using the steering angle control pattern model extracted from the steering angle control pattern model.

The vehicle path calculating step may include calculating a parameter for forming a clothoid curve, which is a continuous curvature based on the determined target position, wherein the clothoid curve can be formed based on the steering angle control pattern model Calculating; And calculating the modified vehicle path based on the parameter.

The clause curve may be a section for avoiding an obstacle while the avoidance section-avoidance section for performing a relatively hasty steering-and the return section for a relatively steep change of the steering. - < / RTI >

Wherein the parameter calculating step calculates the maximum value of the steering angle in the avoidance and return interval and the boundary point of the avoidance and return interval as the parameter through the avoidance interval and the return interval for the obstacle avoidance or path change, And calculating the value of the parameter.

The target position may be a point at which a danger radius of the obstacle meets a danger radius at which the vehicle can prevent the collision on the departure route of the vehicle.

The parameter calculation step may include generating a virtual circle connecting three consecutive points on a path to be changed, and obtaining a radius of curvature and a curvature rate from the result; And calculating the steering angle by taking the obtained curvature change rate as a reference value of the steering angle at the current position of the vehicle in consideration of the direction of the vehicle and the position of the virtual circle.

According to an aspect of the present invention, there is provided a vehicle path calculating apparatus including a target position determining unit for determining a target position for avoiding an obstacle or changing a path based on a current position of the vehicle, And a path calculating unit for calculating the changed spatial or temporal vehicle path by calculating the parameters using the steering angle control pattern model extracted from the driving behavior data.

According to an aspect of the present invention, there is provided a vehicle steering control method including: determining a target position for avoiding an obstacle or changing a path based on a current position of the vehicle; Forming a modified vehicle path for obstacle avoidance or path change based on the position and controlling the steering angle so that the vehicle can move along the path, wherein the path forming step is based on the determined target position Calculating a parameter by using the steering angle control pattern model extracted from the driving behavior data, and calculating the changed spatial or temporal vehicle path.

According to an aspect of the present invention, there is provided a vehicle steering control apparatus including a target position determining unit for determining a target position for avoiding an obstacle or changing a path based on a current position of the vehicle, A vehicle path forming unit for forming a modified vehicle path for obstacle avoidance or path change based on the target position and a steering angle control unit for controlling the steering angle so that the vehicle can move along the path, The controller may calculate the parameter using the steering angle control pattern model extracted from the driving behavior data based on the determined target position to calculate the changed spatial or temporal vehicle path.

According to the vehicle path calculating method and apparatus and the vehicle steering control method and apparatus of the present invention, by ensuring momentary continuity of the steering angle, the change of the dynamic inertia and centrifugal acceleration of the vehicle can be minimized, It is possible to make stable route returning even in the state, and it is effective to provide the driver with the familiarity and comfort by directly utilizing the driving tendency of the human being.

Figs. 1A and 1B are a sectional view of a path shape for obstacle avoidance on a straight road,
FIG. 2 is a graph showing changes in the steering angle and the vehicle direction angle with respect to the mileage in the case of the obstacle avoidance route,
FIG. 3 is a graph showing an approximate human driving steered pattern for obstacle avoidance,
Fig. 4 is a diagram showing a direction result of the vehicle in each section, Fig.
FIG. 5 is a view showing a route of a vehicle generated according to an embodiment of the present invention;
6 is an algorithm flow chart for obtaining a solution of a set variable,
7 is an avoidance path trajectory and a target point decision diagram considering the danger radius _Rmin of the obstacle.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail.

It should be understood, however, that the invention is not intended to be limited to the particular embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component. And / or < / RTI > includes any combination of a plurality of related listed items or any of a plurality of related listed items.

It is to be understood that when an element is referred to as being "connected" or "connected" to another element, it may be directly connected or connected to the other element, . On the other hand, when an element is referred to as being "directly connected" or "directly connected" to another element, it should be understood that there are no other elements in between.

The terminology used in this application is used only to describe a specific embodiment and is not intended to limit the invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In the present application, the terms "comprises" or "having" and the like are used to specify that there is a feature, a number, a step, an operation, an element, a component or a combination thereof described in the specification, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

Unless defined otherwise, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning in the context of the relevant art and are to be interpreted in an ideal or overly formal sense unless explicitly defined in the present application Do not.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In order to facilitate the understanding of the present invention, the same reference numerals are used for the same constituent elements in the drawings and redundant explanations for the same constituent elements are omitted.

Generally, in steering control to follow the path planning and the path image for unmanned driving, the target position is set based on the current position information of each loop control point instantaneous vehicle, the steering angle is calculated, and the steering actuator A method controlled by a specified angle is used. Such a real-time control angle update method is useful in cases where dynamic obstacles are frequent in the surrounding environment, the speed of the vehicle is slow, the vehicle body has a light weight, or a simple mechanical structure. On the other hand, It is not useful in situations where it grows. In other words, when considering the vehicle speed of a general road, when the change of the steering angle does not change smoothly every moment or when the sudden steering angle changes, the danger of the vehicle overturn due to the sudden acceleration of the vehicle is increased or the rider starts / The same shock effect can be given, which causes discomfort.

In order to solve such a problem, when an obstacle is present in the forward direction or a route must be changed, an optimum target point for avoiding an obstacle or changing a route is selected based on the current position of the vehicle, , A method of controlling the steering angle so as to move along the locus after forming the locus to the target point is used.

In the path planning algorithm of the present invention, when the final follow-up / target position is initially determined, a parameter for forming a clothoid curve, which is a continuous curvature, is extracted and a continuous steering angle value is calculated every moment in terms of the steering angle Algorithm.

Since it is not a method of determining the steering control angle based on the present position and the tracking position of the car at every moment, it does not require the current position information of the car at every moment, and therefore it is possible to plan and follow the route even in an area where the GPS does not operate .

The path planning algorithm of the present invention includes a steering angle control method that can provide a driver with stability and comfort by setting and following a path that utilizes human driving tendencies.

When a human is driving, if an unknown obstacle is found in the front, only the front of the obstacle can be identified, and it is difficult to predict the overall shape or future movement. Therefore, if it is confirmed that the obstacle is at the front, the obstacle comes to rotate by turning the steering wheel based on the relative speed at which the obstacle approaches the automobile (section 1 of FIG. 1A) The steering wheel is returned again so that the direction of the vehicle matches the direction of the initial direction or the destination point (section 2 of FIG. 1A). The path shape of the vehicle divided into two sections and the steering angle The change in the travel distance of the vehicle is expressed as shown in FIG. 2, and the solution can be obtained by approximating it and by parameterizing it as shown in FIG.

FIGS. 1A and 1B are diagrams for classifying a route shape for obstacle avoidance in a straight road, and FIG. 2 is a diagram showing a change in steering angle and an automobile direction angle with respect to a mileage in the case of an obstacle avoidance route.

Referring to FIGS. 1A, 1B and 2, when an obstacle is detected in front of a person while he / she is driving, when it is determined that the relative distance to the obstacle is dangerous to some degree, steering starts, . When it is judged that the direction of the vehicle is out of order to avoid collision with the obstacle, the steering angle is returned to the original state. At this time, the front wheel of the vehicle is parallel to the rear wheel, and the direction angle of the vehicle is maintained at a constant angle. Then, in a situation such as a straight road, in order to return to the initial straight line direction, the steering angle is increased in the direction opposite to the initial direction, and then the steering angle returns to the origin in order to keep the direction angle of the vehicle constant. These obstacle avoidance procedures can be divided into two sections, avoidance section and return section, and they are described as section 1 and section 2 respectively.

Section 1 and section 2 differ in the rate of change of curvature. In section 1, humans tend to judge the risk and relate to emotional factors that are relatively steep in steering. It is found that the steady change of steering produces a smooth, low-centrifugal path.

If the steering curve trend is introduced as a solution, it is possible to set the variable to be obtained as shown in the following 3.

In this case, a curve has been developed to ensure the continuity of changes in the steering angle, and polynomials, B-Spline, Cubic-Spline, Trigonometric functions, and clothoidal curve methods. Among these, the method of forming the closode curve has been attempted in the driving control algorithm because the generated curve is closely related to the direction angle of the vehicle and the vehicle steering angle change, and has important characteristics to ensure the continuity of the trajectory and the steering angle change. However, since the chloroid method is a trajectory based on the curvature itself, the orientation is determined according to the distance after the curvature is determined, and the position on the Cartesian coordinate is determined by the determined direction angle. There is a forward definition. In a situation where the steering angle must be changed under the condition of constant speed for the running control, this forward direction has a problem that it can not be obtained by calculating the steering angle result value for the running control. That is, the initial position (pose) and the target posture are set, and the route to the target posture and the steering angle corresponding thereto are determined, but the solution can not be obtained by the analytic method.

K (s) is the curvature at that point with respect to the travel distance, k0 and α are the initial curvature values and curvature variations, respectively, Is a curvature rate.

In the following equation, &thetas; refers to an orientation, and 0 is an initial direction angle.

The x, y coordinates on the Cartesian coordinates of the vehicle at the constant driving distance s are expressed by the following equations,

The above equation can not be solved analytically by obtaining the desired k0, α.

An iterative solution and an approximation method based on geometric simplification are used to solve the above problems, and the appropriateness can be evaluated through a comparative advantage between calculation speed and accuracy. The method of iterative convergence is to find the solution by the iterative convergence of the clause or Frenet equations. In general, it is not possible to guarantee the real time that the path should be planned while driving, , A method of finding an approximate solution by geometric simplification may be useful.

Therefore, the present invention corresponds to an approximate solution method for solving this problem, and is characterized in that human driving tendency is utilized in geometric simplification.

In the present invention, a traveling pattern of a person is analyzed and applied to a route generation of a vehicle. The results of the analysis of human driving pattern are as follows.

The person sitting in the driver's seat while driving does not know all the information about the obstacle or obstacle movement as viewed from above, and the person only looks at the limited area and front. When a person detects an obstacle in the front, the person prepares to change the direction of the vehicle to the left or right, concentrating on the path through which obstacles and obstacles can pass. As the vehicle speed increases, the driver's sense of obstacles becomes more and more sensitive. Thus, people are more responsive to safety, switching or slowing down earlier. Centrifugal acceleration is applied to a person as a person changes direction of the vehicle, and this force is proportional to the square of the curvature and velocity. From this driving experience, the driver tends to minimize curvature, which can be formulated as:

Also, when passing an obstacle, the driver focuses on the movement of the obstacle while viewing the empty space of the front road to increase the angle at which it can steer safely. Until it reaches parallel with the obstacle, the total turning steering angle affects the directional change of the vehicle.

Based on the results mentioned above, the obstacle avoidance path is generated by the following approach. After the lane change is completed by performing lane change for obstacle avoidance, it should return to the original path again. In this case, the direction of the path return point and the return point, that is, pose, can be an available solution by setting the absolute end distance between the end points in the path deviation process as an imaginary circle and defining a return point as a circumferential point. That is, even if the path is not symmetrical as shown in the following figure, the return point can be determined from the viewpoint of the mileage, and then the symmetric clothoid path can be formed.

The equation is as follows.

Therefore, we consider three consecutive points on the path, generate a virtual circle connecting these points, and then obtain the radius of curvature and curvature rate from the result.

The obtained curvature rate is the reference value of the steering control angle at the current vehicle position, and the following steering control angle formula can be obtained in consideration of the orientation of the vehicle and the position of the center point of the imaginary circle .

FIG. 3 shows the result of modeling the steering angle based on the above equation. FIG. 3 is a diagram showing a line and a set variable that approximates a human driving steering pattern for avoiding an obstacle. The geometric approximation of the steepest curve shape is obtained and each solution is obtained by the following procedure.

The result of the direction of the vehicle in each section is shown in Fig. The path of the generated vehicle is shown in Fig.

FIG. 6 is an algorithm flow chart for obtaining a solution of a set variable, and FIG. 7 is a avoidance path trajectory and a target point decision diagram considering a danger radius R _min of an obstacle.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the inventions as defined by the following claims It will be understood that various modifications and changes may be made thereto without departing from the spirit and scope of the invention.

Claims (9)

Determining a target position for avoiding an obstacle or changing a route based on the current position of the vehicle; And
And calculating a changed spatial or temporal vehicle path by calculating a parameter using the steering angle control pattern model extracted from the driving behavior data based on the determined target position. Path calculation method.
The method according to claim 1, wherein the vehicle path calculating step
Calculating a parameter for forming a clothoid curve that is a continuous curvature based on the determined target position, the clothoid curve being formed based on the steering angle control pattern model; And
And calculating the modified vehicle path based on the parameter. ≪ RTI ID = 0.0 > [10] < / RTI >
3. The method of claim 2,
The clause curve may be a section for avoiding an obstacle while the avoidance section-avoidance section for performing a relatively hasty steering-and the return section for a relatively steep change of the steering. And the vehicle path may be a period during which the obstacle avoidance or route change is detected.
3. The method according to claim 2, wherein the parameter calculating step
The maximum value of the steering angle in the avoidance and return interval and the boundary point of the avoidance and return interval are set as the parameters and the value of the parameter is set as the parameter through the avoidance interval and the return interval for obstacle avoidance or path change And calculating a vehicle path for obstacle avoidance or path change.
3. The method of claim 2,
Wherein the target position is a point at which a danger radius of an obstacle and a risk radius at which a vehicle collides against a departure route of the vehicle meet.
The method according to claim 1,
Obtaining a radius of curvature and a curvature rate from the result after creating a virtual circle connecting three consecutive points on a path to be changed; And
And calculating the steering angle by taking the obtained curvature change rate as a reference value of the steering angle at the current position of the vehicle in consideration of the direction of the vehicle and the position of the virtual circle. Vehicle Path Calculation Method.
A target position determining unit for determining a target position for avoiding an obstacle or changing a path of the vehicle based on the current position of the vehicle; And
And a path calculating unit for calculating a changed spatial or temporal vehicle path by calculating a parameter using the steering angle control pattern model extracted from the driving behavior data based on the determined target position. Vehicle path calculating device.
Determining a target position for avoiding an obstacle or changing a route based on the current position of the vehicle;
Forming an altered vehicle locus for obstacle avoidance or path change based on the target position with the current position as an initial position; And
Controlling the steering angle so that the vehicle can move along the locus, wherein the locus forming step
And calculating a changed spatial or temporal vehicle path by calculating a parameter using the steering angle control pattern model extracted from the driving behavior data based on the determined target position.
A target position determining unit for determining a target position for avoiding an obstacle or changing a path of the vehicle based on the current position of the vehicle;
A vehicle locus generator for generating a modified vehicle locus for obstacle avoidance or route change based on the target position with the current position as an initial position; And
And a steering angle control unit for controlling the steering angle so that the vehicle can move along the locus, wherein the vehicle locus forming unit
And calculates the changed spatial or temporal vehicle path by calculating parameters using the steering angle control pattern model extracted from the driving behavior data based on the determined target position.

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